Modification of polymer surfaces by various methods has been practiced for many years. For example, U.S. Pat. No. 2,789,063 describes the use of a sodium/naphthalene reagent to treat poly(tetrafluoroethylene) (PTFE), to modify the surface properties. Numerous other methods have been described using other reagents to chemically modify the surface of various polymers. In addition, other methods of physical treatment, sometimes in the presence of various reagents, have also been used, such as laser ablation, exposure to various plasmas, exposure to electron beams, etc. Some of these methods are capable of forming an image (modified vs. unmodified) on the polymer surface.
U.S. Pat. No. 4,164,463 describes the modification of perfluorocarbon (optionally containing bromine and chlorine atoms) polymer surfaces using sulfur or phosphorous containing compounds. There are several methods of modifying the surfaces disclosed in this patent, among them (at column 8, lines 14-16) the use of "ultraviolet light" to promote the process. It is stated that the "fluoropolymer is exposed to radiation" (as opposed to the instant process where the modifier absorbs the actinic radiation, infra), and it also states that "The amount of solution or liquid in which the fluoropolymer is placed should be such that the starting material is thoroughly wetted, but not so much that the passage of radiation through the liquid is impeded." In the present process it is the modifier which is "activated" by absorbing the actinic radiation (infra).
U.S. Pat. No. 3,563,871 describes the modification of a polychloroprene rubber surface by exposure to radiation with a wavelength of 200 to 350 nm in the absence of oxygen. No other organic compound is present as a modifier.
U.S. Pat. No. 4,824,692 describes the modification of the surface of an ethylenically unsaturated rubber by irradiation of wavelength 100 to 700 nm radiation the presence of selected alkyl halides.
S. Tazuke, et. al., American Chemical Society Symposium Series, vol. 121, Washington, DC, 1980, pp. 217-241, describe the use of photografting to modify polymer surfaces. In this technique a polymerizable vinyl monomer is contacted with a polymer surface and optionally a sensitizer, and the vinyl monomer is grafted to and polymerized on the surface of the polymer, thereby modifying the surface. In the present process, readily polymerizable vinyl monomers are not used as modifying compounds.
It is the object of this invention to provide a process for the modification of various polymer surfaces which is capable of producing images on the polymer surfaces, and which uses ultraviolet and/or visible radiation, which is easy and inexpensive to generate.